The present invention relates generally to produce processing systems, and more particularly to mobile, multiple-stage, energy-efficient produce processing systems for extending the shelf life of produce.
The freshness of fruits and vegetables, generally referred to as produce, is typically defined by the qualities of taste, texture and appearance. Due to certain physiological effects, produce generally begins to deteriorate and lose its freshness at the time of harvest. Once severed from the parent plant, produce no longer has the natural life-sustaining nutrients and fluids and the immune-like system of the plant to combat bacteria, fungi, viruses, and other pathogens which eventually deteriorate the produce. A significant percentage of most produce harvested for shipment and consumption at distant locations are thus lost due to such deterioration. Because of the immense size of the produce industry, it would be highly advantageous from an economic standpoint to preserve recently harvested produce in its fresh, savory condition for an extended period of time. Others have long recognized this. Hence, many different methods for extending produce shelf life have been developed.
Refrigeration has been the most popular method of increasing the useful life of fresh produce. By storing produce at a suitably low temperature, it is possible to extend the freshness by retarding ripening, softening, textural changes and color changes. Lower temperatures also reduce undesirable metabolic changes and moisture losses, and help prevent or slow undesirable growth on the produce. However, depending on the length of time the produce is chilled, refrigeration generally adversely affects taste and quality. Not all produce can be successfully refrigerated to low temperatures. Excessive or extreme chilling, particularly at freezing or near freezing temperatures, can actually damage most types of produce. Even moderate chilling will interfere with the ripening processes of certain types of produce, such as bananas.
Other methods of extending produce shelf life include coating the produce with a protective material, such as wax. However, the success of the coating is related not only to how well the coating protects the produce, but also how well it maintains a desirable appearance of the produce, without affecting its taste. Consequently, the success of this method has been limited. It has also been attempted to lengthen the shelf life of produce through heating to reduce the microorganism population, then refrigerating it at a desirable temperature. The success of this process has been limited in that shelf life has not been significantly increased. It has also been a common practice to harvest produce prior to ripening, then treating it with a ripening agent, such as ethylene gas, to effect ripening. This process has generally provided a low quality, unflavorful product, particularly in the case of tomatoes. Furthermore, the deterioration process begins at the time of harvest regardless of ripeness of the produce.
A more recent approach to extending the shelf life of produce, and tomatoes in particular, has been the employment of genetic engineering techniques to decrease the rate in which tomatoes are affected by microorganisms. Such a process can be viewed as overly complicated to accomplish the goals of extended freshness, and has also enjoyed only limited success. Additionally, certain countries prohibit or strictly regulate the growth, sale, and distribution of genetically altered or modified produce, thus cutting off potential markets to produce growers and distributors.
Once approach to extending the shelf life of produce involves the cleaning of produce to remove pathogens, including fungi, bacteria and viral forms. After harvest, the exterior surface of produce is generally contaminated with fungicides and herbicides as a result of the growing process. Also, environmental pollutants, including various halogenated long-chain hydrocarbons and other synthetic chemical compounds, some of which are known to cause cancer in sufficiently concentrated forms, can sometimes be found on produce being shipped to the United States from foreign sources. Domestically grown produce, while sometimes better in terms of the overall level of contaminants, is still not free from synthetically produced chemicals resulting from herbicide and pesticide applications, from transportation and packaging, and from standard practices in the industry. Thus, it is desirable to have a washing system which provides cleaning of these undesirable pathogens, synthetic chemicals and non-naturally occurring substances from the produce prior to final shipment and sale to consumers.
Many produce cleaning procedures currently used in the industry only involve washing the produce in a water-based bath, or the like, to remove undesirable contaminants existing on the produce. Washing produce in water is limited in its ability to remove many pathogens and other contaminants, however. Therefore, more significant produce cleaning procedures have been proposed in the art.
Another approach to extending produce shelf life is described in U.S. Pat. Nos. 5,229,152 (the ""152 patent) and 5,364,648 (the ""648 patent) issued to Meldrum, the entire specifications of which are expressly incorporated herein by reference. The ""152 and ""648 patents describe a method and apparatus for increasing the shelf life of produce by carefully cleaning the produce and then employing a xe2x80x9csnap freezingxe2x80x9d procedure on the cleaned produce. By xe2x80x9csnap freezingxe2x80x9d it is meant subjecting the produce to temperatures substantially at or below the freezing point of water for a very brief predetermined period of time without the produce flesh being frozen. The method described in the ""152 and ""648 patents include the step of first introducing an item of produce into a heated bath being vibrated generally at a frequency within the range of subsonic to ultrasonic frequencies for a predetermined time preferably shortly after harvest. The combination of the elevated temperature and mechanical vibration makes active and exposes the different micro-organisms which may exist on the produce. Although the process of vibrating the wash bath at ultrasonic frequencies has been successful in removing pathogens and other contaminants from the produce, this produce washing process can be improved upon to further clean the produce and make it safer for human consumption.
Next, the item of produce is transferred to a nucleation vat containing a natural slurry generally comprising natural material extracts including predetermined concentrations and combinations of byproducts from the fruit or vegetable being processed, low solute concentrations of sucrose sugars, fruit and/or acetic acids, and a water solvent carrier. The slurry is maintained at a temperature below the freezing point of water in order to snap freeze the item of produce. The item of produce is then xe2x80x9csnap frozenxe2x80x9d by immersing it in the cold slurry for a brief predetermined period of time. Because the item of produce is held in the nucleation vat for only a brief period of time, the flesh of the item of produce itself will not actually be frozen. Finally, the item of produce is transferred from the nucleation vat to an incubation chamber and held there for a predetermined time, generally at ambient temperatures. This incubation, or drying, stage is used to stabilize and dry the item of produce in order to fully crystallize a film of the slurry on the outer surface of the item of produce. This dried film substantially protects the produce from external pathogens, such as bacteria and fungi. The incubation stage generally takes from several minutes to several hours, and even as long as 48 hours. The item of produce can then be stored or displayed for extended periods of time without significant deterioration or loss of taste, texture and appearance, or the need for refrigeration.
The methodology disclosed in the ""152 and ""648 patents has significantly increased the shelf life of produce as compared to previous conventional methods. However, with respect to the cleaning step, i.e., vibrating the bath at ultrasonic frequencies in order to remove pathogens and other contaminants from the produce, this step can be improved upon to further clean the produce and make it even safer for human consumption. Furthermore, with respect to the drying step, an incubation period of even several minutes per item of produce is generally not preferred by produce growers, processors, and distributors from an efficiency standpoint. This is due, in part, to the advent of highly rapid and mechanized produce processing operations, with the resultant increase in production volume requirements and decrease in the amount of time that produce can economically stay in storage.
Additionally, it is generally necessary to transport the produce, after it has been harvested, to a processing center in order to properly clean and dry the treated produce in accordance with the general teachings of the ""152 and ""648 patents. This need for transportation, and the related need for truckers, loaders, handlers, and other personnel, adds significantly to the operating costs of the produce industry. Additionally, delays in transporting the produce to the processing plant provides an opportunity for pathogens to attack the produce, leading to losses due to rotten or diseased produce that must be discarded.
Therefore, there exists a need for a system capable of rapidly and effectively cleaning the produce and accelerating the drying process in order to crystallize a solute-laden slurry applied to the outer surface of the produce, so that the produce can be adequately protected against pathogens and be made ready for quicker packaging and distribution. This system must be able to clean and dry the treated produce as soon as possible after it has been harvested. Ideally, the system would be mobile, and thus would be able to be positioned in close proximity to area being harvested so that the produce could be immediately processed and treated.
Therefore, It is an object of the present invention to provide a new and improved system of extending the shelf life of produce.
It is another an object of the present invention to create a higher quality washing system for produce, and a cleaner environment in which to handle produce.
It is another object of the present invention to provide an enhanced cleaning system using a multitude of forms of energy to help remove pathogens, synthetic chemicals, long dirt chains, as well as other contaminants.
It is another object of the present invention to provide a new and improved system of drying a solute-laden slurry layer applied to the external surface of an item of produce.
It is another object of the present invention to provide a new and improved system of accelerating the drying of a solute-laden slurry layer applied to the external surface of an item of produce.
It is another object of the present invention to provide a new and improved system of forming protective micro-crystalline structures on and in the external surface of an item of produce.
In order to overcome the aforementioned disadvantages associated with drying the produce and achieve many of the aforementioned objects, the present invention, in accordance with one embodiment of the present invention, provides a system of extending the shelf life of produce, comprising:
immersing the produce in a liquid energizing bath;
subjecting the produce to an electrical waveform for a predetermined period of time in a liquid energizing bath, said waveform removing bacteria and pathogens from the surface of the produce;
immersing the produce in a rinse bath;
applying a solute-laden slurry layer to at least a portion of the external surface of the produce;
subjecting the produce to a first drying procedure, wherein at least a portion of the moisture in the solute-laden slurry layer is removed to form a moisture-reduced slurry layer on the produce;
subjecting the produce to a second drying procedure, wherein at least a portion of the moisture in the moisture-reduced slurry layer is removed to form a protective stratum on the produce; and
subjecting the produce to a third drying procedure, wherein at least a portion of the moisture in the protective stratum is removed to form a crystalline structure on the produce.
In accordance with another embodiment of the present invention, a second system of extending the shelf life of produce is provided, comprising:
immersing the produce in a liquid energizing bath;
subjecting the produce to an alternating electrical waveform for a predetermined period of time in a liquid energizing bath;
subjecting the produce to an ultrasonic waveform to vibrate the produce for a predetermined period of time in the energizing bath, wherein the combination of the ultrasonic waveform and the electrical waveform creates energy to destroy, decouple, disintegrate and/or neutralize pathogens and other contaminants existing on the produce;
applying a solute-laden slurry layer to at least a portion of the external surface of the produce;
subjecting the produce to a first drying procedure, wherein at least a portion of the moisture in the solute-laden slurry layer is removed to form a moisture-reduced slurry layer on the produce;
subjecting the produce to a second drying procedure, wherein at least a portion of the moisture in the moisture-reduced slurry layer is removed to form a protective stratum on the produce; and
subjecting the produce to a third drying procedure, wherein at least a portion of the moisture in the protective stratum is removed to form a crystalline structure on the produce.
In accordance with another embodiment of the present invention, a third system of extending the shelf life of produce is provided, comprising:
subjecting the produce to an ultrasonic waveform to vibrate the produce for a predetermined period of time in the bath;
sweeping the ultrasonic waveform between the first ultrasonic frequency and a second ultrasonic frequency so as to decouple and disintegrate a range of various pathogens and contaminants having different sizes that may exist on the produce;
applying a solute-laden slurry layer to at least a portion of the external surface of the produce;
subjecting the produce to a first drying procedure, wherein at least a portion of the moisture in the solute-laden slurry layer is removed to form a moisture-reduced slurry layer on the produce;
subjecting the produce to a second drying procedure, wherein at least a portion of the moisture in the moisture-reduced slurry layer is removed to form a protective stratum on the produce; and
subjecting the produce to a third drying procedure, wherein at least a portion of the moisture in the protective stratum is removed to form a crystalline structure on the produce.
Other features and advantages of the present invention will be become apparent from the following description and appended claims, taken in conjunction with the accompanying Figures.